Insecticides opportunities

Experience in the baking industry since World War II has shown that proper use of residual spray materials such as DDT and chlordan will most effectively control these casual invaders. When housekeeping in a bakery is maintained as near perfect as possible, the application of a residual layer of toxic insecticide on areas upon which casual invaders are most likely to travel in seeking harborage will effectively kill the invader individual before it has an opportunity to nest. Experience has borne out this theory in a general way, and specific data are now being collected which will describe it in more scientific terms. 

This has been particularly evident with the me thyIcarhamate and phosphoramidothioate insecticides where in almost all cases derivatization has resulted in improved mammalian toxicity. Further, in many cases, equal or greater insecticidal activity has also been observed although in some cases insecticidal activity may be substantially reduced. Improvement in mammalian toxicity has been attributed to the delayed factor provided by the derivatizing group, giving the animal the opportunity to metabolize the compound to non-toxic products. 

Animals often use toxins to immobilise their prey, often insects. Wasps, bees, spiders, mites, scorpions, snakes and other reptiles are all capable of producing potent toxins many of which are insect specific. There is much work in progress around the world examining the opportunities that exist to exploit these toxins to produce new insecticides. This is usually undertaken in two different ways. The first is to determine the mode of action of the natural toxin and to use this novel effect to find synthetic compounds with insecticidal activity in biochemical screens. The second is to attempt to synthesise compounds with the same structural features of the natural toxin and hence with the same mode of action but with better stability following application. The types of compounds that are known are discussed by Blagbrough and Moya13 but none has been commercialised to date. 

In addition, agrochemical companies continue to search for new compounds with novel chemistry and with new modes of action that can be incorporated into crop protection management strategies that will control resistant insects. Furthermore, there is also the opportunity to introduce synergists of insecticides that depress or inhibit the detoxifying enzymes and, thereby, enhance the effectiveness of the compounds. 

Carbamates and OPs are chemicals that are often used as fungicides, insecticides, or pesticides and possess actions similar to nerve agents. These compounds are considered weapons of opportunity since their primary use is not by conventional militaries. In the USA, toxicity from these compounds is fairly rare. In 2006, there were approximately 1,200 cases of carbamate exposures and 1,500 organophosphate exposures documented for children 19 years old and younger (Bronstein et al, 2007). Although there were a few fatalities reported in 2006 from these substances, these fatalities occurred only in older individuals. 

What are the most likely possibilities for the delivery of BT insecticidal activities in the foreseeable future In this author s opinion the greatest opportunity is in the development of new, genetically-manipulated strains of BT applied to crops, forests, and for dipteran insect control by conventional application methods. Our experience at Ecogen has shown... 

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